Paper Number
SC28 

Session
Suspensions and Colloids

Title
The Medium Amplitude Oscillatory Shear (MAOS) of semi-dilute colloid dispersions - Third harmonic of the suspension stress

Presentation Date and Time
October 7, 2014 (Tuesday) 4:50

Track / Room
Track 1 / Commonwealth A

Authors (Click on name to view author profile)

1. Swan, James W. (Massachusetts Institute of Technology, Department of Chemical Engineering)
2. Gurnon, Kate (University of Delaware)
3. Wagner, Norman J. (University of Delaware, Department of Chemical and Biomolecular Engineering)

Author and Affiliation Lines (in printed abstract book)
James W. Swan¹, Kate Gurnon², and Norman J. Wagner^3
1Department of Chemical Engineering, Massachusetts Institute of Technology, Boston, MA 02139; ²University of Delaware, Newark, DE; ³Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE

Speaker / Presenter 
Swan, James W.

Text of Abstract
We study the response of semi-dilute colloidal dispersions under Medium Amplitude Oscillatory Shear (MAOS). Using an excluded annulus model of the hard-core repulsion and hydrodynamic interactions among the particles, we determine the third harmonic of the stress response of a colloidal dispersion in the pair limit. Importantly, the influence of hydrodynamic forces, both in magnitude and in character, on the MAOS of semi-dilute dispersions is made explicit through comparison of such nonlinear rheological properties while varying the ratio of the hard-core to hydrodynamic radius. We show through comparison with experiments that hydrodynamic forces have a considerable effect on the microstructure of dispersions undergoing MAOS. Consequently, the nonlinear, oscillatory rheology of semi-dilute suspensions is quite sensitive to non-conservative, hydrodynamic, forces.